Wireless-telegraph receiving system



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H. J. ROUND WIRELESS TBLBGRAH RECEIVING SYSTEM Filed Feb. 2. 19225A DIRECTIDNAL AERIAL Ebg 1 cIscAoi RESONNCE l umm A n.I:.RI2coRI EIz CASCAD E RESONANCE CIRCUIT B March 22 `1 927;

'Y cAscADE B v Resum/INCE CIRCUIT A 1 cAscAnE IaisoNIIIIcA I CIRCUIT B' IIIIIII Patented Mar. 22, 1927.

UNITED STATES PATENT OFFICE.l

HENRY JOSEPH ROUND, OF LONDON, ENGLAND, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE.

WIRELESS-TELEGRAPH RECEIVING SYSTEM.

Application led February 2, 1923, Serial No. 616,452, and in Great Britain February 21, 1922.

and so that one of' the circuits is tuned to` the signals while the other just avoids signals. Most aerials will be sufficiently aperiodic to be equally well in tune with both the circuits.

Any impulsive type ot atmospheric will produce in the two resonance circuits equal effects differing only in frequency, but in the one circuit the signals will appear in addition to the atmospheric.

The result of an atmospheric at the end of such a cascade arrangement is more or less a modulated continuous wave, so that according to its phase it will add to or subtract from the signal wave in the one circuit, but will appear with its own represent-ative amplitude in the other circuit. At the end of' these two circuits are placed two rectiers as accurately equalized as possible,

whereby the result due to the signals and the atmospheric in the one circuit is rectified and substracted 'from the rectified atmospheric in the other circuit, so that only the difi'erence is recorded.

During a spacing period between signals, there will be no marks on the record, because the atmospheric disturbances will substantially balance out owing to the fact that the oscillations set up in the various cascade circuits are of the same amplitude and phase and differonly slightly in frequency. The marking device of the recorder ,Y

is arranged to be non-responsiye to the com,- paratively small currents which exist as a i \result of the atmospheric oscillations being oi`slightlyv differentfrequency. Therefore -every mark on the record should be read as a signal substantially at all times.

Moreover, in reading the record no at-tention need be paid to the amplitude or direction of the current, that is tosay, a mark out of the zero line will mean the same whether it digresses a long or a short way "from that line and whether it' is on the positive or on the negative side. On which side of the zero line the mark is will depend upon the relation `between the phase of the atmospheric and the phase of the signal.v It they are in phase the effect will be additive and the mark will be positive on the record whereas if they are 180 out of phase the efect will be substractive and the mark will appear on the negative side.

There is, however, one special case to be considered` and that is when the phase difference between the atmospheric and the signal and the strength of the atmospheric are such that the mark due to the signal lies on the zero-line so that a spacing/mgm imitated. Apart from this p 1 whenever there is a mark recorded (posii tive or negative) a signal is present.

Thus an irregular morse is obtained having errors only in the particular case mentoned above with certain phases and strengths of atmospherics.

Such errors may, however, be avoided by employing another aerial, the directional properties of which are oriented exactly as in the first aerial but which is spaced-by some fair proportion of the wave length away from the first one, but in any direction, a similar arrangement being connected to this second aerial; again there will be obtained an irregular amplitude morse having errors only in particular cases, but only in one case are the errors from the two aerials identical. that is, "when the same atmospheric hits both aerials from the direction of the signals. v

This direction is of course theoretically infinitely fine but practical considerations indicate that it is of a certain small angular width depending on the accuracy of' balanc` These two sets of differential e'ects obtained on the two aerials canbe added together, resulting in an irregular amplitude morse which will show a space instead of a mark only when the atmospheric is of a certain amplitude, a certain phase and in the direction of signals.

In the drawings, Fig. l shows diagrammatically by way of example, a two aerial system embodying the features heretofore VAN feoupled to each aerial and so arranged that described, and Fig. 2 shows the relation of their resonance curves are similar and just the resonance curves of theaerial and the do not overlap one another, one of the circascade resonance circuits. cuits being tuned to the signals to be re- Having described my invention what I ceived and the other being tuned so as just claim is: j to avoid the signals, means for rectifying l. In a wireless telegraph receiving Sys-l and opposing the currents at the ends of tem, the combination of two similarly each pair 'of circuits and means for comoriented directional aerials spaced apartby bining and recording the differences. some fair proportion of the wave length to 5. In a Wireless telegraph receiving sysbe received, two cascade resonance circuits teni the combination of two directional coupled to each aerial and so arranged that aerials spaced apart by a fraction of a wave their resonance curves are similar and just length to be received, two resonance circuits do not overlap one another, one of the circoupled to each aerial, a detector coupled to cuits being tuned to the signals to be re-Ieach of said resonance circuits, and a recordceived and the other being tuned so as just ing device, all of said detectors being conto avoid the signals, means :tor rectitying nected in parallel with said recording device. and opposing the currents at the ends ot' each 6. In a wireless telegraph receiving syspair of circuits and means for combining tem, the combination of a pair of directional and recording the dilierences. aerials, a pair of systems each comprising a 2. A method of indicating telegraphic pair of circuits sharply resonant to slightly signals whicli-consists in recording the difdifferent frequencies, a separate detector ference between two rectilied received effects associated with each one of said circuits, said dili'ering only as to their initial radio fredetectors being arranged in pairs and each quency, one of said frequencies being that detector or' a pair being arranged to oppose of the signal and the other slightly different, the output ot its complementary detector, recording the difference and reading the and means to record the resultant detected markings as signals irrespective of the actual current. difference between the rectified effects.

3.' In a wireless telegraph receiving system, the combination of two similarlygorienttem the combination of a pair ot' directional ed directional aerials, two gascade resonance aerials. a pair of systems each comprising a circuits coupled to each aerialand somarpair of similar circuits sharply resonant to ranged that their resonance curves are simislightly different frequencies, one of which lar and just do not overlap one another,

is adapted to receive signal and the other to one of the circuits being tuned to thesignals just avoid signal, means for rectitying and to be received and the gt lier bgling Ytuned opposing the rectified currents, and means just to avoid the signals, a pair ot' detector for combining and recording the resultants devices associated with eachcascade resonof the rectified eli'ects of the two systems. QIleICIs being ance circuit, each pail- 4. In a wireless telegraph receiving sysarranged to oppogethe Aoutputpf its asTsotem, the combination of two aerials spaced ciated resonance circuits, andwa recording apart by some fair proportion ot the wave device, said detectgismb eiiiv'g connected in length to be received, two resonance circuits parallel with saidggecordmgdevice.

7. In a wireless telegraph receiving sysl lll 

